Synthesis and characterization of Parthenium hysterophorus -derived biochar supported titanium dioxide-polyvinyl alcohol ternary composite hydrogel for efficient removal of textile dye

Herein, Parthenium hysterophorus-derived biochar, titanium dioxide and polyvinyl alcohol ternary composite hydrogel was fabricated for efficient removal of Brilliant Green (BG) dye, from aqueous medium. TiO2/biochar composite was synthesized via in situ sol–gel process and incorporated into polyvinyl alcohol matrix to construct the ternary hydrogel. The successful fabrication of ternary composite hydrogel was confirmed initially from its EDX data (76.09% C, 23.25% O, 0.67% Ti). The synergistic interaction of the three components enabled effective dye removal. Approximately 97.4 ± 1.18% of the BG dye was removed within 45 min at pH 7, 0.1 g/L of adsorbent dosage, 20 mg/L initial concentration (BG dye), and temperature of 333K. The hydrogel retained its adsorption performance for up to three cycles with only a slight reduction capacity. For the equilibrium data, Freundlich isotherm showed the best-fitted curve (RBG,Linear2= 0.97, RBG,Non−Linear2= 0.96). For adsorption kinetics, pseudo second order kinetic model with (RBG,Linear2= 0.99, RBG,Non−Linear2= 0.93) showed the best fitting. To investigate the effect of sulfonation and thickness on adsorption behavior, a sulfonated thin film of ternary composite hydrogel with identical composition was fabricated. The thin film attained 94.9 ± 1.32% dye removal efficiency in just 30 min. The effective removal of BG dye by using ternary composite hydrogel highlights its potential as an efficient material for the fabrication of reusable adsorbent for wastewater treatment. The responsible mechanism involved in the removal of BG using prepared adsorbent are electrostatic interaction, π–π interaction, and hydrogen bonding between the functional groups present on adsorbent surface and dye molecules.